Screeding beam for concrete

ABSTRACT

This device, used for screeding newly placed concrete, or similar plastic materials, when constructing floor slabs or similar objects, comprises two horizontal beams capable of movement relative to one another. The beams are attached by means of flexible connecting rods and are moved relative to one another by a crankshaft or weight eccentrically mounted on a motor connected to one of the beams.

United States Patent Berg et al. May 13, 1975 [S4] SCREEDING BEAM FOR CONCRETE 3,256,788 6/1966 Schweihofer et al7 404/120 3,412,658 11/1966 Griffin 404/119 [751 Inventors: 2 2; 3,523,494 8/1970 Kraemer 404/119 panga, o 0 we en [73] Assignee: Dynapac M kin AB Primary Examiner-Louis K. Rimrodt [22] Filed, Dec 6 1973 Assistant Examiner-Steven Hawkins Attorney, Agent, or Firm-Brumbaugh, Graves, [21] App]. No; 422,307 Donohue & Raymond [30] Foreign Application Priority Data [57] ABSTRACT cc 1 9 2 wade l 4/72 This device, used for screedmg newly placed concrete, [52] U S Cl 404mm} 4041118 or similar plastic materials, when constructing floor [51] in. ,CI E64g 21/) slabs or similar objects, comprises two horizontal beams capable of movement relative to one another f h 4 l 1 [58} Field 0 40 H 120 The beams are attached by means of flexible connect- [56] References Cited ing rods and are moved relative to one another by a crankshaft or weight eccentrically mounted on a UNITED STATES PATENTS motor connected to one of the beams.

2,248,247 7/l94l Nichols 404/120 2,372,163 3/l945 Whiteman 404/[19 5 Claims, 4 Drawing Figures PMENTEU MAY 1 31975 7!. 883 .259

SHEET 10F 2 SCREEDING BEAM FOR CONCRETE BACKGROUND OF THE INVENTION Concrete floor construction normally involves the steps of casting, compacting, screeding, and surface finishing. Originally, all this work was carried out by hand, but machines have gradually been developed to accomplish these steps. Vibrating beams, or screcds, which compact or screed the concrete at the same time are generally used on concrete floor slabs.

In order to achieve the necessary compaction effect, the beams are generally equipped with vibrators driven by electric or gasoline engines. The vibrational forces are usually oriented in a plane perpendicular to the surface being compacted. Compaction produces a pressure in the concrete, the result of which is that the concrete is forced up behind the beam. The magnitude of this pressure is partly dependent upon the consistency and thickness of the concrete and partly upon the speed at which the beam is moved across the surface. In practice, it is extremely difficult to obtain a completely uniform and constant speed of travel. In order to limit, as far as possible, the effect of the concrete being forced up, the beam is sometimes arranged as a double beam. However, due to the aforementioned difficulty, even the double beam arrangement is not capable of producing a concrete surface of the smoothness which is often required.

Leveling of a concrete surface by hand with the aid of a straightedge applied in a horizontal sawing motion is known to produce an extremely flat, smooth surface. Such a surface may also be obtained with horizontally oscillating screeding beams, such as those used on machines for constructing concrete roads. However, these machines utilize only a single beam. A consequence of the back and forth sawing motion of a single beam is that the reaction force thus arising must be absorbed either by the frame of the machine on which the beam is mounted or by a heavy frame for the power unit mounted flexibly on the beam.

SUMMARY OF THE INVENTION A screeding beam for compacting concrete or similar plastic masses comprises two parallel, coplanar beams connected by a flexible assembly. The screeding beam further comprises a motor mounted on one of said beams, the shaft of the motor having eccentric means adapted to cause the beams to describe an oscillatory motion relative to one another.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a side view of one embodiment of the present invention;

FIG. 2 is a top view of the embodiment of FIG. 1;

FIG. 3 is a top view of another embodiment of the present invention; and

FIG. 4 is a top view of still another embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS Referring generally to FIGv l, the screeding beam of the present invention is shown. The beam 10 com prises two parallel, coplanar beams 11, 12 which are joined to each other by means ofa flexible assembly 13, which in the preferred embodiement consists of leaf springs. The beams 11, 12 are caused to describe a horizontal, oscillatory motion along their longitudinal axes with the aid of a connecting rod assembly comprising a motor 14, mounted on one of the beams 11 and a connecting rod 15, one end 16 of which is eccentrically mounted on the shaft of the motor 14 and the other end 17 of which is pivotally attached to a bracket mounted on the other beam 12.

By positioning the connecting rod 15 in such a manner that its longitudinal axis is perpendicular to the longitudinal axis of the leafspring 13, the beams ll, 12 are caused to describe an oscillatory motion relative to one another. The direction of this oscillatory motion will be parallel to the plane in which the connecting rod 15 oscillates and in the plane of the beams 11, 12, as shown by the arrows in FIG. 2.

If the screeding beam 10 of the present invention is placed on a horizontal surface, the desired sawing motion is obtained in each beam ll, 12, and by a suitable combination of amplitude and frequency, the effect of manual screeding can be simulated. The reaction force which occurs as a result of the oscillatory motion of the beams 11, 12 is absorbed mutually by the beams I I, 12. As a result of this, the frame which would otherwise be necessary for absorbing the reaction forces, and which was employed in the previously known single beam devices, can be entirely eliminated. Thus, the individual beams ll, 12 incorporated in this screeding beam I0 may be said to form part of an oscillating two-body system with the friction of the beams against the surface acting as a damping factor incorporated into the system.

In order to augment the screeding motion of the beam 10, with a vibrational motion oriented perpendicular to the screeded surface, the beam 10 may be equipped with a vertical vibrator 29. The vertical vibra tor 29 may comprise a motor 19 mounted on one of the beams 12. A weight attached to the shaft of this motor by means of a crankshaft and adapted to reciprocate vertically will provide a vibrational motion oriented perpendicular to the screeded surface. While the screeding beam 10 will be vibrationally rigid in the vertical plane, the vertical vibrator 29 will generate vibrations which cause the beam 10 to vibrate vertically. The result of this vertical vibration will be a compaction effect obtained in addition to the screeding effect.

Referring generally to FIG. 3, another arrangement for a screeding beam 20 is shown. This screeding beam 20 also employs two parallel, coplanar beams 21, 22, a motor 24, a connecting rod 25, one end 26 of which is connected eccentrically to the motor 24 and the other end 27 connected to a bracket 28 attached to the second beam 21. Again, the connecting rod 25 is mounted in a plane perpendicular to the longitudinal axis of the leaf springs 23 connecting the beams 21, 22. In the embodiment 20 of FIG. 3 the oscillatory motion of the beams will no longer be along the longitudinal axes of the beams 21, 22, but will be parallel to the con necting rod 25 as shown by the arrows of FIG. 3.

Referring generally to FIG. 4, a third embodiment 30 of the present invention is shown. This screeding beam 30 employs two parallel, coplanar beams 31, 32, a motor 34, and a pair of leaf springs 33 connecting and separating the beams 31, 32. Attached to the shaft of the motor 34 there is an eccentric weight 35 which rotates in a plane perpendicular to the surface contacted by the beams 31, 32. When the eccentric weight 35 is rotated by the motor 34 the two-body system formed by the beams 31, 32 will oscillate. The oscillation of the beams 31, 32 relative to one another will have an amplitude for each beam which is inversely proportioned to its mass. This embodiment 30 of the invention has the advantage of using a single motor 34 to obtain both compacting and horizontal oscillations.

While the spring assembly of the embodiment shown has been described as comprising leaf springs, as will be understood by one skilled in the art, the leaf springs 13, 23, may be replaced by tie rods which are pivotally and flexibly connected to their respective beams without departing from the disclosed invention.

We claim:

1. A screeding beam for compacting concrete or similar plastic masses which comprises:

a. two parallel, coplanar beams connected by a flexible assembly comprising leaf springs; and

b. a motor mounted on one of said beams, the shaft of said motor having an eccentrically mounted connecting rod attached to the other of said beams adapted to cause said beams to describe an oscilla tory motion relative to one another.

2. The screeding beam of claim 1 further comprising a weight eccentrically mounted on the shaft of said motor.

3. The screeding beam of claim 2 wherein said eccen trically mounted weight rotates in a plane which is perpendicular to the longitudinal axes of said beams.

4. The screeding beam of claim 1 further comprising means for vertically vibrating said beams.

5. The screeding beam of claim 4 wherein said means for vertically vibrating said beams comprises a vertical vibrating element mounted on one of said beams. 

1. A screeding beam for compacting concrete or similar plastic masses which comprises: a. two parallel, coplanar beams connected by a flexible assembly comprising leaf springs; and b. a motor mounted on one of said beams, the shaft of said motor having an eccentrically mounted connecting rod attached to the other of said beams adapted to cause said beams to describe an oscillatory motion relative to one another.
 2. The screeding beam of claim 1 further comprising a weight eccentrically mounted on the shaft of said motor.
 3. The screeding beam of claim 2 wherein said eccentrically mounted weight rotates in a plane which is perpendicular to the longitudinal axes of said beams.
 4. The screeding beam of claim 1 further comprising means for vertically vibrating said beams.
 5. The screeding beam of claim 4 wherein said means for vertically vibrating said beams comprises a vertical vibrating element mounted on one of said beams. 